mac80211: Be more careful when changing channels.

If we cannot set the channel type, set the channel back to the
original.

Don't update the driver hardware if nothing actually changed.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 16 insertions, 3 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 4bc8a9250cfd..88b0884ebe6a 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1215,6 +1215,9 @@ static int ieee80211_set_channel(struct wiphy *wiphy,
 {
         struct ieee80211_local *local = wiphy_priv(wiphy);
         struct ieee80211_sub_if_data *sdata = NULL;
+        struct ieee80211_channel *old_oper;
+        enum nl80211_channel_type old_oper_type;
+        enum nl80211_channel_type old_vif_oper_type= NL80211_CHAN_NO_HT;
 
         if (netdev)
                 sdata = IEEE80211_DEV_TO_SUB_IF(netdev);
@@ -1232,13 +1235,23 @@ static int ieee80211_set_channel(struct wiphy *wiphy,
                 break;
         }
 
-        local->oper_channel = chan;
+        if (sdata)
+                old_vif_oper_type = sdata->vif.bss_conf.channel_type;
+        old_oper_type = local->_oper_channel_type;
 
         if (!ieee80211_set_channel_type(local, sdata, channel_type))
                 return -EBUSY;
 
-        ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
-        if (sdata && sdata->vif.type != NL80211_IFTYPE_MONITOR)
+        old_oper = local->oper_channel;
+        local->oper_channel = chan;
+
+        /* Update driver if changes were actually made. */
+        if ((old_oper != local->oper_channel) ||
+            (old_oper_type != local->_oper_channel_type))
+                ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+
+        if ((sdata && sdata->vif.type != NL80211_IFTYPE_MONITOR) &&
+            old_vif_oper_type != sdata->vif.bss_conf.channel_type)
                 ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_HT);
 
         return 0;